The actual fact is that you can find a lot of people who have been in the business for a long time, and they’ve been in the business for a long time. The sinus opening due to clinical hair hiding disease is mostly at the gluteal groove, and the sinus tract travels mostly to the cranial side, rarely downward toward the anal canal. The skin surrounding the fistula is red and swollen, often with scarring, and in some cases hair is visible. A probe can be inserted 3-4 cm, and when squeezed, a thin, light-smelling fluid can be discharged. The fistula is characterized by pus flow, the amount of pus is related to the length of the fistula, the amount of new fistula flow more pus, secretions irritate the skin and itchy discomfort, when the external mouth is blocked or pseudo-healing, pus accumulation in the fistula, local swelling and pain, and even fever, later closed fistula break, the symptoms only disappear. Due to poor drainage and recurrent abscesses, multiple external openings can also break down. In larger and higher anal fistulas, there is often fecal matter or gas discharge from the external opening. On examination, the external opening is often a papillary protrusion or a bulge of granulation tissue, and a small amount of pus is discharged by squeezing, mostly from a single external opening, near the anus. There are also multiple external openings with subcutaneous fistulae between them and hardened and atrophic skin. There are also multiple external openings on both sides, and the fistulae are “horseshoe shaped” and can be palpated by rectal palpation in the lesion area as hard nodules or cords with tenderness. If the external opening is not neat, not elevated, with a submerged edge, and the granulation is grayish or with a thin, cheese-like discharge, tuberculous anal fistula should be suspected. Of course, the above mentioned is only from the clinical manifestation. The most important thing is the diagnosis of the disease by rectal ultrasound. The main pathological manifestations of anal fistula are the external mouth, fistula, branched canal, and internal mouth. The rectal ultrasound can show the endografts, fistulae and exografts, with a slightly increased blood flow signal around the fistulae. The main pathological manifestations of the sacrococcygeal hair-bearing sinus include the primary canal, sinus cavity, secondary canal, and hair. Rectal ultrasound shows normal rectal morphology in patients with hairy sinuses, while hair-like punctate or linear echogenicity is seen in the echogenic part of the sacrococcygeal sinus orifice, with enhanced subcutaneous thickening and more blood flow signal. The location of fistulae differs between anal fistulae and hidradenoses: fistulae are irregular and extend toward the rectum of the anal canal, while fistulae in hidradenoses are mostly cephalad, with a few caudal, and the tip of the sinus tract is mostly blind.